1. Field of the Invention
The present disclosure relates to an information processing apparatus and an original reading apparatus.
2. Description of the Related Art
Conventionally, an information processing apparatus and an original reading apparatus comprising an image reading apparatus is well-known. Further, as the image reading apparatus used in the information processing apparatus such as a copying machine etc., the original reading apparatus and the like which performs the so-called “original flow reading” is known. Such an apparatus conveys an original onto a platen glass one by one with an original conveyance apparatus. The original is exposed to light by an exposure device fixed to its conveyance path to read the image of the original. Further, the original reading apparatus which performs “double-side simultaneous reading” is increasing. In such an apparatus, reading of both the front and back surface of the original is performed by one-time conveying of the original. Such original reading apparatus intends to respond to the needs to efficiently transform a document into an electronic format. To improve efficiency in reading, two original reading apparatuses are provided in the original reading apparatus. When performing “double-side simultaneously reading”, first, the image data of the front surface of the original and that of the back surface of the original read are sequentially output to a data output line. Then, the image data read is temporarily stored in a memory of the apparatus. Thereafter, the stored image data is sequentially read from the memory.
Further, there is known an information processing apparatus such as the copying machine and the like which temporarily stores the image data read in the original reading apparatus in the memory, such as a hard disc, DRAM (Dynamic Random Access Memory) and the like. In case of a copying machine, the image data is repeatedly read for the desired number of printings in an arbitrary order to print out the image. This type of copying machine controls such that an identical original image obtained by one-time reading is read from the memory for a plurality of times in an appropriate order.
As mentioned, in the information processing apparatus such as the copying machine and the like, frequently, the image data of the original is temporarily stored in the memory of the apparatus. In this case, the image data is temporarily stored in the memory of the apparatus. Due to this, when printing is finished, the image data remains in the memory of the apparatus. Therefore, the remaining data may be read by a third party unless it is overwritten by new data. The remaining data may include the contents of the document and the like which is highly confidential. Thus, some mechanism to promptly erase data in the memory to secure confidentiality and privacy is required.
To this problem, some methods for erasing data in the document from the memory after the printing and the like are disclosed in Japanese Patent Application Laid-open Nos. 2005-236578 and H09-223061.
In the Japanese Patent Application Laid-open No. 2005-236578, an image forming apparatus is provided. The image forming apparatus is capable of preventing leakage image data temporarily stored in the original image read means of the image forming apparatus. To prevent leakage of secrets, the image forming apparatus is formed such that the erasure of the image data will be finished almost simultaneously with completion of image data transfer. However, in such a configuration, reading, transferring and overwriting for erasure of the image data need to be performed in parallel, which takes time in processing. In addition, this makes the circuit complicated and increase in size thereby increasing the cost.
Japanese Patent Application Laid-open No. H09-223061 provides a method and device for processing information which can input/output information based on management information while keeping secrecy. In the Japanese Patent Application Laid-open No. H09-223061, it is determined whether a secret document mode is set or not, and when that mode is not set, image data read is stored in a hard disk together with a file allocation table (FAT). When the stored image data are output, the processing is immediately finished. When the secret document mode is set, the image data read is stored in the hard disk together with the FAT. After the stored image data are output, the image data stored in the hard disk and the FAT corresponding to the image data are erased. Then, the processing is finished. Such a configuration enables to surely maintain confidentiality, however, it takes time to discriminate whether it is in the secret document mode or not.
Further, such “double-side simultaneously reading” may be performed as follows. First, the image data of the front surface and the back surface read are output to the data output line in order. Then, the image data read is temporarily stored in a memory of the apparatus. Thereafter, the image data stored is sequentially read from the memory in an order of the front surface and the back surface for every page to transfer the image data read.
When the operation of reading and transferring the image data is performed in parallel with the operation of overwriting for erasure of the image data, access speed or access band to the memory which performs each processing in parallel may be insufficient according to the memory used or its configuration. This prevents the image data from being read and output from the memory at a desired speed. If an operating speed of the memory is accelerated for obtaining desired speed, amount of energy consumption is increased. Further, if the width of the memory data bus is increased to increase the access band to the memory, the cost may be increased.
Due to such restriction, it is sometimes configured such that, after the operation of reading and transferring the image data is completed, the operation of overwriting erasure is performed to the image data stored in the memory. When configured as above, it takes time from the completion of the operation of reading and transferring the image data to the completion of the operation of overwriting for erasure of the image data. Further, due to such a configuration, until the operation of overwriting for erasure of the data is completed, reading of the original to be read next (next original) is not accepted. Thus, it takes time to perform the overwriting for erasure processing and may give influence in convenience of use of the apparatus.